to (one's) dying day

For the entirety or remainder of one's life. to my dying day, I will never forgive him for what he's done to our family. Despite all her doctors' warnings, my grandmother smoked cigarettes like a chimney to her dying day.

to your dying day

for the rest of your life.

1967 George Mackay Brown A Calendar of Love This one always was and ever will be to his dying day a garrulous long-winded old man.

till/to/until your ˌdying ˈday

for as long as you live: I swear I won’t forgive her to my dying day!

dying day, to one's

For the rest of one’s life. The English poet George Sandys used the expression as long ago as 1599: “To have a sight of her sometime before their dying-dayes.” The cliché usually appears in a somewhat melodramatic or hyperbolic context, such as “I’ll never forget this garden, not to my dying day.”